🚨 Never stop insulin without urgent medical advice. Sudden omission can cause severe hyperglycaemia and, in insulin-deficient states, diabetic ketoacidosis (DKA).
🩺 If vomiting, abdominal pain, rapid breathing, ketones, or drowsiness → treat as an emergency.
ℹ️ About
- 📚 Always check the BNF insulin monograph for preparation-specific prescribing and local protocols.
- 💉 Insulin safety: use the correct device and concentration. UK insulin is commonly U-100 (100 units/mL).
- 🧾 For subcutaneous insulin, use insulin syringes or insulin pens (never “guess” volumes with non-insulin syringes).
- ⚠️ High-risk medicine: prescribe clearly in units (never “U” or “IU”), double-check dose, and document indication.
Mode of action
- 🧬 Soluble (short-acting) human insulin (e.g. Actrapid) binds insulin receptors → ↑ glucose uptake (muscle/fat), ↓ hepatic glucose output, and shifts potassium into cells.
- ⏱️ SC onset ~30 minutes; peak ~2–4 hours; duration ~6–8 hours (can vary by site, dose, perfusion).
- 🧂 Drives intracellular K+ shift via Na⁺/K⁺ ATPase activation → useful in hyperkalaemia (temporary effect).
Indications
- 🍬 Diabetes: treatment of hyperglycaemia (including correction dosing) and as part of basal–bolus regimens.
- 🏥 Inpatient control: VRII/VRIII (variable rate IV insulin infusion) for acute illness, peri-operative fasting, or when oral intake is unreliable.
- 🧂 Hyperkalaemia: shifts potassium intracellularly (bridge while definitive measures work: calcium for membrane stabilisation; dialysis/resin/diuretics as appropriate).
Dosing (always follow local protocol + BNF)
✅ Dosing is individualised. Always follow your local diabetes/hyperkalaemia pathway and verify in the BNF/drug datasheet.
| Use |
Typical example |
Frequency |
Route |
Key safety points |
| 🍬 SC correction (Actrapid) |
Common starter correction doses might be 4–6 units (varies widely) |
PRN |
SC |
🧠 Recheck capillary glucose; avoid “stacking” doses; ensure basal insulin continues in type 1. |
| 🏥 VRII/VRIII |
Insulin infusion rate adjusted to bedside glucose (protocol-driven) |
Continuous |
IV infusion |
🧪 Hourly CBG initially; provide substrate fluid with glucose + potassium as per protocol; never stop long-acting basal in type 1. |
| 🧂 Hyperkalaemia shift |
10 units soluble insulin IV with glucose (common adult protocol) |
STAT |
IV |
⚠️ Hypoglycaemia risk for 4–6+ hours → mandatory glucose monitoring. |
🧂 Hyperkalaemia regimen (typical adult example — follow local policy)
- 💉 Soluble insulin 10 units IV PLUS glucose 25 g IV (examples: 50 mL of 50% glucose OR 125 mL of 20% glucose).
- 🕒 Potassium typically falls within 30–60 minutes; effect is temporary (hours).
- 🔁 Check serum potassium and repeat ECG/CBG as per pathway.
VRII/VRIII preparation (safety essentials)
- 🧪 Follow your local JBDS-based protocol (“VRIII/VRII” naming varies).
- 💧 Ensure a concurrent substrate infusion (glucose-containing fluid ± potassium) unless contraindicated.
- 🩺 Monitor: hourly CBG until stable, then per protocol; monitor electrolytes (especially K+).
- 🧯 Hypoglycaemia rescue must be immediately available (oral glucose/IV glucose as appropriate).
- 🧠 Type 1 diabetes: do not omit basal insulin even while on VRII/VRIII (prevents ketosis).
Interactions
- 📚 See BNF for full list.
- ⬆️ Insulin requirements may increase with steroids, infection, thiazides; ⬇️ with reduced intake, renal failure, alcohol, some antibiotics.
- 🫀 Beta-blockers can mask adrenergic warning symptoms of hypoglycaemia (sweats/palpitations).
Cautions
- ⚠️ Be ready to treat hypoglycaemia and hypokalaemia.
- 🫘 Renal impairment increases hypoglycaemia risk (reduced insulin clearance).
- 🍽️ If oral intake is variable, consider VRII/VRIII or regimen adjustment rather than repeated PRN boluses.
Side effects
- 🍭 Hypoglycaemia (most important acute risk).
- 🧂 Hypokalaemia (especially with IV insulin for hyperkalaemia).
- 💉 Injection-site lipohypertrophy (with repeated SC injections — rotate sites).
References
